Intraocular lenses having crossed haptics

ABSTRACT

A crossed haptics attached to an intraocular lens suitable for implantation in either a phakic or an aphakic eye and a method for implanting and releasing the haptics after implantation in the eye, wherein. The lens comprises a very thin, deformable optic having two pairs of haptics attached to the optic by means of two stems 180° apart on the circumference of the optic, the stems being wider and thinner at the base attached to the periphery of the optic, and tapering to a narrower and thicker tip to which each haptic is connected at opposite edges of the stem. Each haptic optionally sweeps about the periphery of the optic so that the angle subtended by a radial line extending from the center of the optic through the center of a footplate and a second radial line extending from the center of the optic through the center of the stem to which it attaches is about 135°. Also disclosed is a haptic design comprising four footplates which are all independently attached to an optic transition area. The optic transition area is the area where the haptics engage the optic. This embodiment is preferably inserted into the eye by a rolling method. As such, this embodiment provides a lens with excellent flexibility and allows the haptics to be placed inside a rolled optic and return to their natural shape when unrolled.

[0001] The present application is a Continuation-in-part application ofU.S. Ser. No. 09/084,989, filed May 28, 1998, now allowed; the contentsof which are expressly incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention The present invention relates the fieldof ophthalmology, and particularly to crossed haptics for intraocularlenses (“IOL”), the intraocular lenses comprising the haptics aresuitable for implantation of an appropriate optic in either a phakic oran aphakic eye. One suitable optic is a thin lens where the optic isrolled into a circle or oval and the haptics are placed inside the opticwhen rolled.

[0003] 2. Anatomy of the Eye

[0004] The human eye functions much like a camera. It accommodates tochanging lighting conditions and focuses light rays originating fromvarious distances from the eye. When all of the components of the eyefunction properly, light is converted to impulses and conveyed to thebrain where an image is perceived. See Northwest Kansas Eye Clinicwebsite Dec. 06, 1999, “How The Eye Works,” Glaucoma, Ocular Anatomy andFunction.

[0005] Light rays enter the eye through a transparent layer of tissueknown as the cornea. The surface that a contact lens rests upon is theouter surface of the cornea. The outer surface is also known as theepithelium layer of the cornea. The inner surface of the cornea is theendothelium. As the eye's main focusing element, the cornea takes widelydiverging rays of light and bends them through the pupil, the dark,round opening in the center of the colored iris. With the conditionMyopia or nearsightedness, if the eye is too long, or the cornea has toomuch focusing power, images focus in front of the retina. The light rayshave passed the correct focal point by the time they reach the retina.The retina then sends an “over-focused,” blurry image to the brain.Hyperopia, or farsightedness, is the opposite of myopia; images focus ona point beyond the retina. This condition is a result of an eye that istoo short or a cornea that lacks the necessary refractive power to focusimages on the retina. Note the main focusing element of light raysentering the eye is the cornea. Light rays then pass through theanterior chamber of the eye, which is the area between the inside of thecornea and the iris.

[0006] The lens of the eye is located immediately behind the iris andpupil. The purpose of the lens is to make the delicate adjustments inthe path of the light rays in order to bring the light rays into focusupon the retina, the membrane containing photoreceptor nerve cells thatlines the inside back wall of the eye. The photoreceptor nerve cells ofthe retina change the light rays into electrical impulse and send themthrough the optic nerve to the brain where an image is perceived.

[0007] For the purpose of the present disclosure, common definitionsknown to one of ordinary skill in the art are used for common parts ofthe eye. For example, the cornea is understood as being the transparent,outer “window” and primary focusing element of the eye. The outer layerof the cornea is known as epithelium. Its main job is to protect theeye. The epithelium is made up of transparent cells that have theability to regenerate quickly. The inner layer of the cornea,endothelium, is also made up of transparent tissue, which allows lightto pass; however, the endothelium does not regenerate when damaged.

[0008] The pupil is the dark opening in the center of the colored iristhat controls how much light enters the eye. The colored iris functionslike the iris of a camera, opening and closing, to control the amount oflight entering through the pupil.

[0009] The lens is the part of the eye immediately behind the iris thatperforms delicate focusing of light rays upon the retina. In personsunder 40, the lens is soft and pliable, allowing for fine focusing froma wide variety of distances. For individuals over 40, the lens begins tobecome less pliable, making focusing upon objects near to the eye moredifficult. This is known as presbyopia.

[0010] The retina is the membrane lining the back of the eye thatcontains photoreceptor cells. These photoreceptor nerve cells react tothe presence and intensity of light by sending an impulse to the brainvia the optic nerve. In the brain, the multitude of nerve impulsesreceived from the photoreceptor cells in the retina is assimilated intoan image.

[0011] Finally, the anterior chamber is the small space between thecornea, endothelium, and the iris. The pupil is the central hole in theiris. The natural lens of the eye is located immediately behind theiris. The anterior chamber is filled with a clear fluid that carriesoxygen and nutrients to the cornea and lens. Metabolic waste productsproduced by the lens and cornea are also removed by this fluid. An organcalled the ciliary body located behind the iris constantly producesfresh fluid called aqueous. The fluid then circulates from behind theiris through the pupil, moves through the anterior chamber and finallyexits through a drainage mechanism called Schlemm's Canal. See FIG. 1.

[0012] The entrance to the canal is a filtering network called thetrabecular meshwork. The fluid produced by the ciliary body meets someresistance when exiting the anterior chamber through the trabecularmeshwork causing pressure to build up inside the eye. The balancebetween the amount of aqueous production and the ease of drainagethrough the trabecular meshwork is very important. If the aqueous isproduced at higher rate than the rate of drainage, the pressure insidethe eye will rise. If it rises high enough, damage to the optic nervewill occur with associated loss of visual function. The condition ofunbalanced pressure in the eye is called glaucoma. Uncorrected glaucomacan lead to permanent blindness.

[0013] 2. Description of the Prior Art

[0014] Ophthalmologists have been developing the art of implanting anartificial lens in the human eye for many years, both to replace thenatural lens which has been removed due to disease (an aphakic eye), andto supplement the natural lens with a corrective lens (a phakic eye).

[0015] Various pathologic disease processes can cause deterioration ofthe natural lens requiring removal of the lens, most notably theopacification of the lens which occurs in cataracts. In thedevelopmental stage, cataracts may be treated by frequent changes ofeyeglass prescription. When useful vision is lost, the natural lens isgenerally removed, either intact or by emulsification. When the lens hasbeen removed, correction is achieved either through spectacles, contactlenses, or an intraocular implant.

[0016] Over fifty years ago, an ophthalmologist implanted the first lensafter the removal lo of the natural lens due to cataracts (aphakic eye).The early lenses were placed in the anterior chamber of the human eye.From the initial implants, surgeons wanted a lens where radically onesize would fit all eyes. The initial lenses were constructed from onepiece of material where the optic and haptic footplates were part of asolid piece of material. A typical lens from the late 1970's is shown inFIG. 2.

[0017] By the early 1980's, technology was developed to where the hapticfoot plates and the optic could be connected from one piece of materialusing stems approximately 200 microns in diameter. For anterior chamberaphakic implants the lens are still very popular in 1999; however, over97 percent of all cataract operations are done by placing a lens in theposterior chamber of the eye. Most surgeons begin using posteriorchamber lens because anterior chamber lens required radial sizing to fitthe eye and blocked the aqueous flow through a portion of the trabecularmeshwork. If the sizing was not perfect, additional pressure was placedon the trabecular meshwork, which projected additional pressure onSchlemm's Canal, this further restricted aqueous flow. Blocking aqueousflow increases the internal pressure of the eye (i.e., glaucoma). Anadditional problem with the anterior chamber lens is the footplates areapproximately 250 microns thick, which restricts the portion of thetrabecular meshwork where the footplate is contacting the tissue. Aftermost of the profession changed to posterior chamber lens, a smallincision posterior chamber lens was developed. The state of the artanterior chamber lens still requires an incision larger than the opticdiameter of the lens. After twenty years of use, the Kelman lens isstill a popular anterior chamber lens for cataract surgery. A typicalKelman lens is shown in FIG. 3.

[0018] From the drawings, it is apparent that the Kelman lens is muchmore flexible than the earlier models. However, the manufacturer stillmarkets six different radial lengths of the lens ranging from 11.5 to14.5 millimeters. Recently, samples for the lens were obtained and theforce required to flex the lens one millimeter ranged from 1.5 to 4.0grams. The manufacturer supplies a chart, which does not show insertingthe lens in an eye where the flexure is greater than one millimeter.

[0019] Optical displacement is the amount of movement of the lens alongthe optical axis of the lens when compressed using the at restmeasurement as reference (see FIG. 4). Another way of stating opticaldisplacement is when the lens fits into a large eye there is very littlepressure applied to the haptics to position the lens. When the same lensis placed into a smaller eye more pressure is required to fit the lensinto the eye. When the additional pressure is necessary the lens willmove forward toward the endothelium.

[0020] The difference in position between the small eye and large eyeanterior placement is the optical displacement. Recent measurements ofthe Kelman style lens versus the current invention show comparableoptical displacement. Both style lenses have optical displacement ofless than 25 micron.

[0021] When compressed, the dimension referred to as Sagitta in anuncompressed lens increases. The difference in the Sagitta of a lens atrest and the same dimension of a compressed lens is opticaldisplacement.

[0022] Due to the problems and the availability of a very good posteriorchamber lens, much of the aphakic eye surgery previously done withanterior chamber lens changed to the posterior chamber lens. The largestadvantage of the posterior chamber lens was the development of posteriorchamber lens that will pass through a small incision. By 1990 over 80percent of cataract surgery was being done with small incision posteriorchamber lens.

[0023] In the 1980's, surgeons began doing Radial Keratotomy (RK) tocorrect myopia. Later surgeons learned Photorefractive Keratectomy (PRK)was a more effective treatment of myopia and in the 1990's LASIK (laserin situ keratomileusis) surgery became popular. LASIK is effective overa much larger power range.

[0024] In RK, and PRK the cornea is cut to relax the tissue, whichreduces the amount of bending of light as it passes into the eye. LASIKsurgery removes a layer of tissue from the middle layer of the cornea,which has the effect of flattening the cornea, to reduce the bending oflight as it enters the eye. PRK and LASIK surgery is done using a laser.Of course, most vision correction is accomplished using contact lens andspectacles.

[0025] As an alternative to the laser surgeries, contact lens, andspectacles, ophthalmologists are implanting lens in the eye with thenatural lens still in place (phakic eye). The lens can also be used inconjunction with another method of treatment. For example, for a highmyopic patient the ophthalmologist may make part of the correction usingPRK or LASIK surgery, and then implanting the lens for the remainder ofthe needed correction. The lens can also be used to correct forhyperopia (farsightedness) using a positive powered lens. The depth ofthe anterior chamber of the human eye is deeper for a myopic eye thanfor a hyperopic eye; therefore, the clearance to place the lens andhaptic in the anterior chamber is less. The depth of the anteriorchamber of the eye varies and so does the width of the eye. One wouldnormally expect a deep eye to be narrower than a shallow eye; therefore,the haptics on all lenses being placed in the anterior chamber of thehuman eye must be sized to fit the eye.

[0026] Making different lengths of haptics and having the surgeonmeasure the anterior diameter of the eye can accomplish the sizing. Asecond method is to have the haptic portion of the lens maintain a nearconstant force when compressed to fit a smaller eye.

[0027] For almost twenty years, small incision posterior chamber lenshave been available. A small incision lens for the anterior chamber isneeded. For the phakic eye, the physical dimensions of the lens in theaxial plane must be small. Nothing is being removed from the eye, so theamount of space to place the lens optic and haptics are limited.

[0028] Traditionally vision problems such as myopia, hypermetropia andastigmatism have been treated with corrective lenses in spectacles orcontact lenses. However, as significant improvements and experience hasbeen gained, the use of intraocular implants using corrective lenses hasincreased.

[0029] Generally, the lens separates the aqueous humor from the vitreousbody. The iris separates the region between the cornea or anterior ofthe eye and the lens into an anterior chamber and a posterior chamber.The lens itself is contained in a membrane known as the capsule orcapsular sac. When the lens is removed from the eye, the capsule mayalso be removed (intracapsular excision), or the anterior portion of thecapsule may be removed with the lens leaving the posterior portion ofthe capsule intact (extracapsular extraction), often leaving small foldsor flaps from the anterior portion of the capsule. In an intraocularimplant, the artificial or prosthetic lens may be inserted in theanterior chamber, the posterior chamber, or the capsular sac. Theartificial lenses are usually fixedly attached within the eye, either bystitching to the iris, or by some supporting means or arms attached tothe lens, often in the form of sweeping arms called haptics.

[0030] Examples of lens for implantation in the anterior chamberinclude: U.S. Pat. No. 4,254,509, issued Mar. 10, 1981 to Jerald L.Tennant (an accommodating lens with 2 haptics 180° apart archedposteriorly to optic, with an arc at the end of each haptic definingfeet); U.S. Pat. No. 4,816,032, issued Mar. 28, 1989 to Jens G. Hetland(optic with a hole in the center to equalize pressure and preventglaucoma, having 2 loop haptics); and Soviet Invention Certification No.SU 1377086, published Nov. 4, 1986 (optic with two pairs of crossedhaptics).

[0031] An example of a lens for implantation in the posterior chamber isshown in U.S. Pat. No. 5,108,429, issued Apr. 28, 1992 (optic withconcentric support ring attached by micrometers controlled by computerto adjust the position of the lens for loss of focal power orastigmatism resulting from the surgery).

[0032] A number of advances have dealt with implants in the capsularbag, which attempt to take advantage of the capsular membrane to avoiddamage to the tissue of the eye. Among them are: U.S. Pat. No.4,711,638, issued Dec. 8, 1987 to Richard L. Lindstrom (2 hapticsattached to one quadrant of optic, forming semicircles on opposite sidesof the optic, and open ended 180° from their point of attachment); U.S.Pat. No. 4,795,460, issued Jan. 3, 1989 to Aziz Y. Anis (2 hapticscircumferentially surrounding optic by about 350°, attached to the optic180° apart); U.S. Pat. No. 4,804,361, issued Feb. 14, 1989, also to Anis(optic surrounded by supporting ring connected to optic by twoelongated, curved members); U.S. Pat. No. 4,842,6900, issued Jun. 27,1989 to Fred T. Feaster (a single haptic overlapping itself with a nooseat the end for guiding the haptic); U.S. Pat. No. 4,863,463, issued Sep.5, 1989 to Tik T. Tjan (optic with concentric supporting ring attachedby two elongated, curved members); U.S. Pat. No. 4,878,911, issued Nov.7, 1989 to Aziz Y. Anis (optic with concentric supporting ring connectedby 2 straight segments 180° apart); U.S. Pat. No. 5,171,320, issued Dec.15, 1992 to Okihiro Nishi (optic with grooves on periphery receivinganterior flaps of capsule); U.S. Pat. No. 5,266,074, issued Nov. 30,1993 to Nishi, et al. (same as above, but with different shapes forperiphery); U.S. Pat. No. 5,366,501, issued Nov. 22, 1994 to David W.Langerman (optic with two concentric support rings attached by straightbars, the outer ring angled anteriorly); U.S. Pat. No. 4,655,775, issuedApr. 7, 1987 to Thomas J. Clasby III (optic with ridges to offset opticfrom posterior surface of posterior chamber, having 2 bent haptics); andU.S. Pat. No. 4,950,290, issued Aug. 21, 1990 to William Kammerling(lens to reduce posterior capsular opacification, having biconvex opticwith helically shaped loop haptic sloping 10° anterior to the optic).

[0033] Examples of correcting lenses are described in U.S. Pat.4,585,456, issued Apr. 29, 1986 to John M. Blackmore (corrective lens incontact with natural lens, having 2 appendages or haptics fitting intothe ciliary sulcus); U.S. Pat. No. 4,769,035, issued Sep. 6, 1988 toCharles D. Kelman (corrective lens with folding optic and two broadhaptics 180° apart, each having an arc at the free end to define feet,the optic being folded and inserted in the posterior chamber through thepupil); U.S. Pat. No. 5,098,444, issued Mar. 24, 1992 to Fred T. Feaster(optic glued to anterior surface of natural lens); U.S. Pat. No.5,258,025, issued Nov. 2, 1993 to Fedorov, et al. (optic with sameradius of curvature as natural lens, two broad haptics having feetfitting in Zinn's zonules); U.S. Pat. No. 5,480,428, issued Jan. 2,1996, also to Fedorov, et al. (corrective lens floating in the eye); andour own pending application (a deformable intraocular corrective lenswith 2 curved haptic 180° apart).

[0034] Examples of accommodating lenses are shown in U.S. Pat. No.5,443,506, issued Aug. 22, 1995 to Antoine L. Garabet (varying the powerof the lens by a fluid loop through a first optic, the fluids havingdiffering refractive indices and responding to electrical impulses fromthe ciliary body); U.S. Pat. No. 5,489,302, issued Feb. 6, 1996 to BerntC. Skottun (lens with fluid and membranes responding to change inpressure caused by ciliary muscle, changing volume of fluid andrefractive index of lens).

[0035] U.S. Pat. No. 4,573,998, issued Mar. 4, 1986 to Thomas P.Mazzocco, describes various arrangements of haptics, none of which arecrossed, and various methods for implanting deformable intraocularlenses, none of which describe using a viscoelastic material to joinseriated sutures. U.S. Pat. No. 4,994,080, issued Feb. 19, 1991 toDennis P. Shepard, shows an optic with at least one opening to improvefocusing for depth, with embodiments having either 2 or 4 haptics, nonebeing crossed. U.S. Pat. No. 5,522,890, issued Jun. 4, 1996 to Nakajimi,et al., discloses a deformable lens having two haptics attached to theoptic using right angled reinforcements at the periphery of the opticwhich are thicker than the periphery, the lens being folded into a tubeshape for implantation in the eye.

[0036] Some foreign patents showing slightly different arrangements ofthe haptics include: U.K. Patent No. 2,124,500, published Feb. 22, 1984(annular ring attached to optic by fibers); German Patent No. 3,722,910,published Jan. 19, 1989 (two haptics, each having a substantiallyquarter moon shape); French Patent No. 2,653,325, published Apr. 26,1991 (an annular haptic bound to haptic by a bridge, and 180° away by aconvex loop); French Patent No. 2,666,503, published Mar. 13, 1992 (twohaptics joining optic on the same side, extending in semicircle onopposite side of optic, and having a stop to prevent crossing ofhaptics); German Patent No. 4,040,005, published Mar. 26, 1992 (twohaptics spreading out from a common bridge to optic); and French PatentNo. 2,687,304 published Aug. 20, 1993 (optic with annular support ringjoined to optic by two bridges).

[0037] Despite the advances, there remain problems with intraocularimplants which may be ameliorated by the improved haptics and method ofreleasing the haptics of the present invention inside the bulb of theeye. When an intraocular lens is inserted in the eye, an incision ismade in the cornea or sclera. The incision causes the cornea to vary inthickness, leading to an uneven surface which causes astigmatism. Theinsertion of a rigid lens through the incision, event with compressiblehaptics, requires an incision large enough to accommodate the rigid lens(at least 6 mm), and carries with it the increased risk ofcomplications, such as infection, laceration of the ocular tissues, andretinal detachment. Deformable intraocular lenses made frompolymethylmethacrylate (“PMMA”), polysulfone, silicone or hydrogel maybe inserted through a smaller incision, about 4 mm or less.

[0038] Nevertheless, it is critical that the lens be properly centeredand properly fixed so that it does not slip out of position. In ananterior chamber implant, the lens should be positioned between thecornea and the iris, but avoiding contact with either to prevent cornealdamage, proliferation of corneal epithelium on the anterior surface ofthe lens causing opacification, or iritis. If the lens is not positionedproperly with respect to the pupil, too much light may be admitted tothe retina, causing serious vision difficulties. The haptics or lenssupport generally lodge in the angle of the anterior chamber, but it isdesirable that the haptics be as flexible as possible while keeping thearea of surface contact between the haptic and the eye tissue as smallas possible to avoid swelling, laceration, infection, or other damage tothe eye tissue.

[0039] The anterior chamber of the eye is filled with the aqueous humor,a fluid secreted by the ciliary process, passing from the posteriorchamber to the anterior chamber through the pupil, and from the angle ofthe anterior chamber it passes into the spaces of Fontana to thepectinate villi through which it is filtered into the venous canal ofSchlemm. The lens must be positioned so the flow of fluid is not blockedor glaucoma may result. If the haptics fit slightly too tight, thepatient experiences pain and the lens may have to be removed. If thehaptics are slightly too loose, the lens may move into the endothelialcells on the inside of the cornea causing permanent loss of vision.

[0040] Posterior chamber and capsular bag implants involve both similarand different considerations. In posterior chamber implants, the hapticsnormally lodge in the ciliary sulcus, entailing the same considerationswith regard to tissue swelling and damage through laceration. Mostposterior chamber implants are placed in in the posterior capsule inorder to take advantage of the insulating properties of the capsulemembrane. Here, it is desirable to stretch the capsule as much aspossible, vaulting the optic posteriorly to avoid having the anteriorflaps proliferate and opacify the anterior surface of the lens, and tostretch the capsule taut. The corrective lens for the phakic eye must beextremely thin in order to fit into the limited space in either theanterior or posterior chambers with the natural lens still in place, butmust have some area of thickness at the periphery of the lens to supportattachment of the haptics.

[0041] Regardless of the type of implant, some means of centering theimplant is essential. Currently artificial lenses are implanted usingspecial tools to compress the haptics, such as forceps or cannulas, orrely on microhooks to manipulate the optic through a hole in the surfaceof the optic. Haptics designed to center in the eye and means forcompressing the haptics without the use of bulky tools during centeringis therefore desirable.

[0042] The present invention solves these problems by a deformableintraocular lens having two pairs of crossed haptics with footplatesconnected to the optic by a stem. The lens is inserted into the eyeusing a unique method of compressing the haptics by seriated suturestemporarily joined using a viscoelastic material, which is dissolvedafter centering the lens in the eye.

[0043] Although the Soviet Invention Certificate SU 1,377,086 also showscrossed haptics, it is noted that (1) the optic is rigid, requiring alonger incision (6 mm) and the increased risk of complications duringinsertion, as well as restricting use to anterior chamber implants; (2)the haptics do not have footplates, placing more surface area of thehaptic in contact with the eye tissue; (3) there is not stem betweenadjacent haptics, but rather each haptic is individually attached to thehaptic, requiring the periphery of the lens to be thick enough forattachment of the haptics; and (4) the haptics extend outwardly from theoptic for ¾ of their length before turning concavely towards the lens,virtually precluding compressing the haptics either in front of orbehind the lens, presenting a longer profile for insertion through theincision.

[0044] Thus, none of the above inventions and patents, taken eithersingularly or in combination, are seen to describe the instant inventionas claimed. Hence the crossed haptics for intraocular lenses solving theaforementioned problems is desired.

[0045] 3. Discussion of Deflection Formulas

[0046] All materials have some deflection when force is applied. For thepurpose of haptic design, a material is chosen that has a flexibilitythat allows the lens to remain stationary in the plane parallel with thecentral axis of the lens, yet is flexible when constructed to thedesired thickness in the radial plane. As stated above, the position ofthe optic is very important, with potentially serious adverse effectsoccurring when an optic is improperly positioned. For the most part, thelens haptics are constructed from plastic, which responds to deflectionaccording to the following formula:

f≈WL ³ /EI

[0047] Where:

[0048] f=Deflection of the haptic

[0049] W=Amount of force applied to the end of the haptic

[0050] L=Length of the haptic

[0051] I=Moment of inertia of the haptic material.

[0052] ≈ is a sign to show numbers are proportional instead of equal. Inthe present case, constants have been omitted.

I≈hw³

[0053] h=vertical height of the haptic

[0054] w=width of the haptic

[0055] E=Modulus of elasticity of the haptic material.

[0056] The modulus of elasticity (E) is the ratio of the increment ofunit stress to increment of unit deformation within the elastic limit ofthe material. See Standard Handbook for Mechanical Engineers, TheodoreBaumeister, Editor, and Marks Editor, 1916 to 1951, McGraw Hill BookCompany, New York Sixth Edition Pages 5-42.

[0057] According to Hooke's Law, when force is applied along an axis theincrease in length due to application of the force divided by theoriginal length of the member along the axis to which force is appliedis strain. See Mechanics of Materials by E. P. Popov Professor of CivilEngineering University of California Prentice-Hall, Inc. EnglewoodCliffs, N.J., Page 29.

[0058] Strain is a dimensionless quantity, and is very small except formaterials such as rubber. Stress is the amount of force applied to amaterial divided by the cross Sectional area of the material where thestress was applied. When plotting a relationship between stress andstrain, there is a portion of the diagram that is linear. Thedeflections where the stress strain diagram is linear do not cause apermanent deformation of the material to which the stress was applied.For some materials, such as cast iron and concrete the portion of thecurve where there is no permanent deformation is extremely small. Forsome alloy steels the curve is linear almost to the rupture point of thematerial. Up to some point, the relationship between stress and strainmay be said to be linear for all materials.

[0059] This is known as Hooke's Law. Stress is directly proportional tostrain and the constant of proportionality is called the elasticmodulus, modulus of elasticity, or Young's modulus. The elastic modulushas been bench tested and calculated for many materials and published inengineering and other scientific handbooks. The formula for deflectioncan be stated as the amount of deflection of a beam, the haptic, isproportional to the applied force times the length of the deflectedobject, haptic, to the third power divided by the modulus of elasticitytimes a coefficient and the moment of inertia of the material beingdeflected. Id. at 435. The inertia of the material in a rectangularshape can be expressed as the width of the haptic times the height ofthe haptic to the third power divided by a constant. Id. at 424. Inaddition, when a material of rectangular shape is deflected and theamount of deflection is held constant, over time the amount of stress inthe material will reduce. For example, haptics of rectangular dimensionswere made using the present invention. The haptics were deflected threemillimeters and the applied force measured. After twenty-four hours, theamount of applied force to retain the three-millimeter deflection haddecayed to less than 25 per cent of the original deflection force.

[0060] 4. Discussion of Mechanical Properties

[0061] Shear stress is defined as stress arising in practice whenapplied forces are transmitted from one part of a body to the other bycausing stresses in the plane parallel to the applied force. See FIG. 5.Id. at page 3.

[0062] Stress in a beam caused by bending can be represented by theequation:

Sb=Mc/I

[0063] Where

[0064] Sb=the stress on the beam from bending.

[0065] M=the bending moment which is the force times the bending arm.

[0066] I=the moment of inertia for the cross Section

[0067] c.=The distance for the stressed edge to the neutral axis of thebeam.

[0068] In addition, when an object in compression rests against anotherobject that is in equilibrium, the transferred pressure is equal to theapplied force divided by the area in contact. Which can be written as:

P=F/A

[0069] Where:

[0070] P=pressure applied to support the member that is compressed.

[0071] F=force applied to hold compressed member in equilibrium.

[0072] A=area between the compressed member and supporting member thatis in contact.

[0073] 5. Discussion of Haptic Deflection

[0074] Using the deflection formulas one can see the deflection isproportional to the applied force times the length of the beam (orhaptic) to the third power. The modulus of elasticity for a givenmaterial is constant if one assumes the material to be homogenous.

[0075] As shown by FIG. 6, the moment of inertia for a rectangularstructure is the width of the cross Section of the material times theheight of the cross Section of the material to the third power.

[0076] Therefore one can write the formula for deflection as:

f≈WL ³ /EI

[0077] Where:

I≈hw³

[0078] Therefore:

f≈WL ³ /E hw ³

[0079] Since E is a constant, the formula can be written:

f≈WL ³ /hw ³

[0080] The textbook formula is shown for deflection in the verticalplane. The current invention desires to eliminate as much movementaxially, which is known as anterior displacement. Yet the currentinvention desires to make the haptics much more flexible than thecurrent state of the art. The flexure equation must be written as twoways. The first equation represents deflection in the radial plane andcan be written as:

f≈WL ³ /tw ³

[0081] Where:

[0082] t=thickness of the haptic and is measured parallel to the centralaxis of the lens.

[0083] w=the width of the haptic and is measured along the radial plane.

[0084] W=applied force in the radial plane.

[0085] L=length of the beam.

[0086] If “t” is decreased while “w” is held constant, the amount ofdeflection for a given force will increase. Conversely, as “t” decreasesthe amount of force required to deflect the beam is proportionallydecreased. However, as “w” is decreased the amount of force to deflectthe beam is decreased by the third power of the width. Therefore theradial deflection of the beam or haptic is much more influenced by thewidth of the beam or haptic than the thickness.

[0087] For deflection in the axial plane the equation can be written as:

f≈WL ³ /wt ³

[0088] Where:

[0089] W the applied force in the axial direction.

[0090] L=the length of the beam or haptic.

[0091] 'w=the width of the beam or haptic measured in the radial plane.

[0092] 't=the thickness of the beam or haptic measured in the axialplane.

[0093] Deflection in the vertical plane is proportional to the thirdpower of the thickness and proportional to the width of the haptic orbeam. Since radial displacement is proportional to the third power ofthe width and proportional to the thickness, one can readily see byincreasing the thickness of the beam and reducing the width of a beam,the beam will become much more flexible while resisting deflection inthe axial plane. For the desired lens, increasing the thickness reducesthe axial displacement and decreasing the width of the haptic, increasesthe radial flexure.

[0094] The haptics on the Kelman anterior chamber lens that is widelyused have a haptic that is approximately 175 microns square. Whereas,certain embodiments of the current invention have haptics that areapproximately 175 by 100 microns, the 100-micron dimension is found inthe radial plane and is raised to third power. Therefore, the currentinvention has a cross sectional area that is designed to be much moreflexible than the current state of the art lens. The Kelman Lens withthe overall radial diameter of 14 millimeters has haptic members thatare approximately 7¼ millimeters from the optic to the first footplateand an additional 4½ millimeters from the first footplate to the secondfootplate. Since the second footplate pivots from the first footplate,it is obvious the two-footplates do not exert the same amount of forcefor a given displacement. The haptic members on such embodiments areapproximately 8 millimeters from the optic to the footplate on eachhaptic. The dimensions will cause the current invention's footplates tobe slightly more flexible than the first footplate of the Kelman Lens.The second footplate of the Kelman Lens will be more flexible than thecurrent invention, since the Kelman Lens second haptic pivots from thefirst haptic. Therefore, haptics diagonally across on the Kelman Lenswill have approximately the same force while the alternate haptics havea different force. The force will attempt to reach equilibrium, so thelens may de-center to balance the forces. The current invention has allthe forces equal so the lens centration is much more easily achieved.

SUMMARY OF THE INVENTION

[0095] The present invention comprises crossed haptics attached to anintraocular lens suitable for implantation in either a phakic or anaphakic eye and a method for implanting and releasing the haptics afterimplantation in the eye. The lens comprises a very thin, deformableoptic having two pairs of haptics attached to the optic by means of twostems 180° apart on the circumference of the optic, the stems beingwider and thinner at the base attached to the periphery of the optic,and tapering to a narrower and thicker tip to which each haptic isconnected at opposite edges of the stem. Each haptic optionally sweepsabout the periphery of the optic so that the angle subtended by a radialline extending from the center of the optic through the center of afootplate and a second radial line extending from the center of theoptic through the center of the stem to which it attaches is about 135°.The lens is symmetrical about an axis extending through the opposingstems, with each haptic crossing either over or under the hapticconnected to the opposing stem on the same side of the axis. Thisembodiment of the present invention may be inserted into the eye byusing a previously prepared seriated suture joined by a viscoelasticmaterial to fold the lens in a tubular shape and compress the haptics,inserting the lens in the eye, centering the lens, dissolving theviscoelastic material with saline solution, and removing the seriatedsuture by pulling a free end of the suture left outside the eye duringinsertion. When released, the footplates of the four haptics lie on thecircumference of a circle concentric with the optic, subtending foursubstantially equal arcs.

[0096] Accordingly, it is a principal object of the invention to providecrossed haptics for intraocular lenses suitable for implantation intoeither a phakic or an aphakic eye which may be centered in the eyeeasily in the form of a deformable lens having crossed haptics withfootplates at their free ends which may be inserted in the eye usingseriated sutures temporarily joined by a viscoelastic material tocompress the lens and haptics in a tubular shape, dissolving theviscoelastic material and removing the suture after centering the lens.

[0097] It is another object of the invention to provide crossed hapticsfor intraocular lenses suitable for implantation into either a phakic oran aphakic eye which may be centered in the eye easily in the form of adeformable lens having two pairs of crossed haptics with footplateswherein the position of the lens is fixed in the eye by four foot plateslying on the circumference of a circle concentric with the optic andsubtending substantially equal arcs.

[0098] It is a further object of the invention to provide crossedhaptics for intraocular lenses suitable for implantation into either aphakic or an aphakic eye in which damage to the tissue of the eye isreduced by minimizing haptic contact with the eye to four footplatessized and shaped to exert a minimum of pressure on the tissues of theeye.

[0099] Still another object of the invention is to provide crossedhaptics for intraocular lenses suitable for implantation into either aphakic or an aphakic eye having two pairs of crossed haptics attached tothe optic by a pair of stems in which the lens may be implanted in theanterior chamber, the posterior chamber, or the capsular sac, dependingon the conformation of the lens.

[0100] It is an object of the invention to provide improved elements andarrangements, thereof for the purposes described which is inexpensive,dependable and fully effective in accomplishing its intended purposes.

[0101] It is another object of the invention to provide a haptic designcomprising four footplates which are all independently attached to anoptic transition area. The optic transition area is the area where thehaptics engage the optic. This embodiment is preferably inserted intothe eye by a rolling method. As such, this embodiment provides a lenswith excellent flexibility and allows the haptics to be placed inside arolled optic and return to their natural shape when unrolled.

[0102] These and other objects of the present invention will becomereadily apparent upon further review of the following specification anddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0103]FIG. 1 is a view of an anterior chamber of an eye and Schlemm'sCanal.

[0104]FIG. 2 is a view of a prior art, one-piece lens.

[0105]FIG. 3 is a view of a prior art Kelman lens.

[0106]FIG. 4 is a graph showing optical displacement.

[0107]FIG. 5 is a figure showing a measurement of a value for sheerstress.

[0108]FIG. 6 is a figure demonstrating values of the moment of inertia.

[0109]FIG. 7 is a front elevational view of crossed haptics forintraocular lenses according to the present invention.

[0110]FIG. 8 is a horizontal section of the human eye.

[0111]FIG. 9 is a view of crossed haptics for intraocular lensesaccording to the present invention with the lens and haptics compressedfor insertion into the eye.

[0112]FIG. 10 is a plan view showing the preparation of suture materialused to insert the lens of the present invention into the eye.

[0113]FIG. 11 is a plan view of the a first embodiment of an intraocularlens with crossed haptics according to the present invention adapted forinsertion into the anterior chamber of an aphakic eye.

[0114]FIG. 12 is a plan view of a second embodiment of an intraocularlens with crossed haptics according to the present invention adapted forinsertion into the posterior chamber of an aphakic eye.

[0115]FIG. 13 is a plan view of a third embodiment of an intraocularlens with crossed haptics according to the present invention adapted forinsertion into the posterior chamber of a phakic eye.

[0116]FIG. 14 is an embodiment of an intraocular lens of the presentinvention featuring four haptics all independently attached to the optictransition area.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0117] The present invention relates to crossed haptics for intraocularlenses and a method for inserting the lens into the bulb of the eye andreleasing the haptics. Haptics are spring-like structures which supportthe optic of an intraocular lens implant in order to maintain the lensin a relatively fixed position within the eye.

[0118]FIG. 7 shows an intraocular lens, designated generally asreference 10 in the Figures, showing exemplary crossed haptics 60according to the present invention. The lens comprises a central opticalportion referred to as the optic 20. The optic 20 is designed to replacethe natural lens in an aphakic eye, or to supplement and correct defectsin the natural lens in a phakic eye. The optic 20 will generally beconstructed in varying thicknesses, shapes (generally disk shaped, withits outer surfaces biconvex, plano-convex, etc.), and focal powers orproperties according to the application. The crossed haptics 60 of thepresent invention are designed to be used with optics 20 havingdifferent optical properties. However, they are intended for use withand are integral with deformable optics 20 made frompolymethylmethacrylate (“PMMA”), polysulfone, silicone or dydrogel,preferably PMMA, and are capable of being deformed by compressing,rolling folding, stretching, etc. for insertion into the eye through asmall incision, but being somewhat resilient and having memorycharacteristics to revert to their original shape when the forceprocuding deformation is removed. In the preferred embodiment, the optic20 is about 6 mm in diameter and the edge of the optic is about 0.050 mmthick.

[0119] A pair of substantially flat stems, designated generally as 30,extend from the edges of optic 20, each stem having a line of symmetryseparated from the other by approximately 1800. The base 40 of the stem30 is wide and thin where it attaches to the edge of the optic 20, beingabout 3 mm wide and 0.05 mm thick. As it extends radially from optic 20,the stem 30 becomes progressively narrower and thicker, being about 1 mmwide and 0.127 mm thick at the tip 50 or free end of the stem 30.

[0120] Each stem 30 has a pair of haptic arms 60 attached to oppositeedges of the stem 30 near the tip 50. The width of the stem 30 at itsbase 40 and the thickness of the stem 30 at its tip 50 provide strengthand a secure anchor for mounting the haptic 60 arms to the optic 20,while retaining a sufficiently flexible stem 30 to manipulate thehaptics 60 as set forth below.

[0121] Each of the haptic arms 60 has a footplate 70 at its free end.The footplates 70 are small, rounded protrusions at the end of thehaptics 60 extending slightly laterally from the outer edge of thehaptic 60. The haptic arms 60 are arcuately shaped and extend fromopposite sides of the tip 50 of the stem 30, being concave relative tothe edge of the optic 20. Along a radial line extending from the centerof the optic 20, the tip of the stem is about 4.75 mm from the center ofthe optic 20 and the outer edge of each footplate 70 rests in a circleabout 7 mm from the center of the optic 20. Each haptic 60 sweeps aboutthe periphery of the optic 20 so that the angle subtended by a radialline extending from the center of the optic 20 through the center of afootplate 70 and a second radial line extending from the center of theoptic 20 through the center of the stem 30 to which it attaches is about135°. The lens 10 is symmetrical about an axis extending through theopposing stems 30, with each haptic 60 crossing either over or under thehaptic 60 connected to the opposing stem 30 on the same side of theaxis.

[0122]FIG. 8 is a horizontal section of the bulb of the human eye 100and depicts many of the features of the eye's anatomy discussed above.The eye 100 is coated by three tunics: an outer layer composed of athick sheath called the sclera 110 covering the posterior ⅚ of the eye,and a transparent covering called the cornea 105 over the anterior ⅙; amiddle layer called the choroid 120 posteriorly, containing thevasculature and musculature of the eye, joining the ciliary body 140 andiris 150 anteriorly; and an inner layer called the retina 130,comprising a nervous membrane. The tunics are pierced posteriorly by theoptic nerve 135 and blood vessels of the retina. The iris 150 is anopaque diaphragm having an aperture called the pupil 160 at its center,and expands or contracts the opening of the pupil 160 by contracture andrelaxation of the ciliary muscle in the ciliary body 140 to regulate theflow of light into the eye 100. The natural crystalline lens 190 issuspended between the iris 150 anteriorly and the vitreous body 195posteriorly by ligaments known as the zonules of Zinn 192 attached tothe muscles of the eye 100 in the ciliary body 140. At the junctionbetween the iris 150 and the ciliary body 140 is a shallow depressionknown as the ciliary sulcus 145. The iris 150 and pupil 160 divide theanterior region of the eye 100 into the anterior chamber 170 and thepsoterior chamber 180, which are filled with the aqueous humor, a fluidsecreted by the ciliary process and flowing from the posterior chamber180 through the pupil 160 into the anterior chamber 170. At the angle175 of the anterior chamber 170 (at the junction of the cornea 105, andthe iris 150), the fluid is filtered through the spaces of Fontana andthe pectinate villi and drains through the sinus venosus sclerae, orcanals of Schlemm 172. The lens 190 is contained within a thin membranecalled the lens capsule (not shown).

[0123] The haptics 60 of the present invention may be used for implantsinto the anterior chamber 170, the posterior chamber 180, or theposterior portion of the lens 190 capsule. FIG. 11 shows theconformation of the IOL, 10 for implantation in the anterior chamber 170of an aphakic eye. As shown in the plan view, the optic 20 is in ananterior plane, and the stems 30 are angled posteriorly so that theoptic 20 is vaulted anteriorly, with the footplates 70 occupying a planeposterior to the tips 50 of the stems 30. FIG. 12 shows the conformationof an IOL 10 of the present invention for implantation in the posteriorchamber 180 of an aphakic eye. As shown in the plan view, the optic 20is in a posterior plane, and the stems 30 are angled posteriorly so thatthe optic 20 is vaulted posteriorly, with the footplates 70 occupying aplane anterior to the tips 50 of the stems 30. FIG. 13 shows theconformation of the IOL 10 for implantation in the posterior chamber 180of a phakic eye. As shown in the plan view, the optic 20 is in aposterior plane, and the stems 30 are angled posteriorly so that theoptic 20 is vaulted posteriorly, with the footplates 70 occupying aplane anterior to the tips 50 of the stems 30.

[0124] It will be appreciated that in each of the three conformationsshown above, the optic 20, the tip 50 of the stem 30, and the footplates70 of the haptics 60 each occupy a different frontal or coronal plane,with the tip 50 of the stem 30 always occupying the middle plane. Whenthe haptics 60 are released, the footplates 70 occupy positionssuperior, inferior, and lateral to the stems 30. As a consequence ofthis geometry, in this embodiment the stems 30 do not come into contactwith a tissue of the eye 100, and are prevented from lacerating ordamaging the tissues.

[0125] It will also be appreciated that when the haptics 60 are releasedin the eye 100, the haptics 60 expand so that, in the average human eye100, the footplates 70 rest on the circumference of a circle concentricwith the optic 20 and subtend four substantially equal arcs of 90° eachabout the circumference of the circle. The footplates 70 are so sizedand shaped that surface contact with and pressure applied to the tissuesof the eye 100 are kept to a minimum to avoid complications due toswelling, lacerations or other damage to the eye tissue. For phakiceyes, a corrective IOL may be implanted with the lens 10 centered in theanterior chamber 170, the footplates normally resting in the angle 175of the anterior chamber 170, or in the posterior chamber 180 between theiris 150 and the natural lens 190, the footplates 70 normally resting inthe ciliary sulcus 145. For aphakic eyes, the IOL 10 may be implanted inthe anterior chamber 170 with the footplates 70 normally resting in theangle 175 of the anterior chamber 170, or in the posterior chamber 180with the footplates 70 normally resting in the ciliary sulcus 145, or inthe capsular bag with the footplates 70 within and stretching theposterior portion of the capsule of the lens 190.

[0126] A method for implanting the haptics 60 and releasing the haptics60 after implantation in the eye 100 can now be described. A piece ofsuture material is cut into a first piece 80 and a second piece 90 whichare seriated as shown in FIG. 9. The two pieces of suture material aresequenced with a pair of outer zones 95, each with a single threadarranged in substantially S-shaped loops, and a center zone 85 betweenthe two outer zones 95, in which the first piece and the second piecehave overlapping lengths with the S-shaped loops paralleling each other.The suture material is coated with a viscoelastic material which isunreactive to and harmless to the eye 100, preferably a heavy layer orpaste of chondroitin sulfate, and allowed to dry. The center zone 85 mayreceive a second coat of the viscoelastic material to ensure that thecenter zone 85 has a thicker layer of the viscoelastic material than theouter zones 95 and that the first piece 80 is temporarily bonded to thesecond piece 90.

[0127] After the viscoelastic material has dried, the seriated suturematerial is tied around the lens 10 until the optic 20 is deformed intoa tube and the haptics 60 are compressed and tucked either anteriorly orposteriorly to the optic 20, as shown in FIG. 9. The surgeon inserts thelens 10 into a minimal incision in the cornea 105 or sclera 110 andpositions the lens 10 in the eye 100, leaving a loose end of first piece80 and second piece 90 outside the eye. After positioning the lens 10,the surgeon inspirates an irrigating solution, preferably salinesolution, onto the viscoelastic paste, which dissolves the paste. Sincethe outer zones 95 have a thinner layer of paste, the outer zones 95tend to dissolve before the center zone 85. As the paste dissolves, theS-shaped loops of the outer zones tend to unwind and lengthen, releasingthe haptic 60 arms, which spring back to their original conformation dueto the memory characteristics of the lens 10 material, the surgeontweaking the position of the lens 10 by manipulating the haptics as theyunwind, if necessary. By the time the outer zones 95 are free of theviscoelastic paste, the outer edges of the footplates 70 rest againstthe tissue of the eye 100 in a circular pattern. The size of the circledepends on the size of the eye 100. Typically, the human eye 100 is 11.5to 13.5 mm in diameter.

[0128] Additional irrigating solution is inspirated to the center zone85 until all the paste is dissolved, separating the first piece 80 ofsuture material from the second piece 90. The suture material can thenbe removed from the eye 100 by gently pulling the loose end of firstpiece 890 or second piece 90.

[0129] Thus, the crossed haptics 60 of the present invention and themethod of inserting and releasing the haptics 60 present a means forsupporting an IOL 10 which offers improved centering of the lens 10while minimizing damage to the tissue of the eye 100.

[0130] In another embodiment of the present invention, the lens isrolled and passed through the cornea. This method is discussed below andin U.S. Ser. No. 08/914,767 (filed Aug. 20, 1997 and incorporated hereinby reference). This is a preferred method of insertion for theembodiment of the present invention discussed below.

[0131] A preferred embodiment of the present invention is depicted inFIG. 14. In this embodiment, to achieve strength, the current hapticdesign has a transition area, 2. The haptic transition area, 2, startsat the optic edge with a wide area in contact with the edge of theoptic. The transition area is the same thickness as the optic edge wherethe transition area and the optic edge are in contact, 3. As the haptictransition area extends radically away from the optic, the membernarrows, 4, until a desired width to allow the maximum shear stress frombending to remain relatively constant. As the distance from the opticincreases radically, the thickness of the haptic is increased. The widearea of the haptic at the optic edge adds strength to the structurewhile allowing flexibility of the optic for rolling. Axial flexibilityis less desirable once the transition to the haptic has been achieved,so the thickness of the haptic increases as the width decreases. Thecross sectional area has changed in width and thickness in such a ratioas to allow the maximum shear stress from bending to remain relativelyconstant.

[0132] The length of the haptic is also proportional to the amount offorce required to flex the haptic through a given distance. One methodof increasing the effective length of the haptic on the currentinvention is splitting the haptic, 5. At the radial distal end of thehaptic transition area the haptic is split into two members. Themembers, 6, travel parallel for some distance, which allows the hapticto move further away from the optic. As the haptic extends radicallyuntil approaching tissue when implanted in a small eye the hapticchanges direction, 7, and moves toward a point approximately 15-30degrees, preferably 25 degrees, from the center line, 8, of the haptictransition area and along a radically outward circle, 9, that is thedesired maximum size of the haptics. The outer edge, 11, of the hapticfootplate, 70, rests tangentially to the radically outward circle, 9,that is the desired maximum size of the haptic. The haptic arms, 60, arebent to where the footplates, 70, are placed inside the optic area, 20.The optic area is rolled to where the footplates are enclosed inside theoptic area for ease of insertion into the eye through a small incision.

[0133] Since the force necessary to deflect the lens three millimetersis significantly less than the force required to flex the current stateof the art lens one millimeter, much less force is exerted on the tissueof the eye. Therefore, the thickness of the footplates, 70, can besignificantly thinner than for the current lens designs and the forceexerted on the tissue of the eye is still much less per square area thanthe current state of the art lens. A lens manufactured to the currentstate of the art will rest just toward the center of the eye fromSchlemm's canal, which will effectively block the canal in the areawhere the footplates are located. A thin lens footplate will rest towardthe iris from Schlemm's canal and not block the flow of aqueous out ofthe eye.

[0134] In this embodiment of the present invention, the haptics areplaced inside a rolled optic and return to their natural shape after theoptic was unrolled. A desirable feature of the crossed haptic embodimentof the present invention is the four haptic footplates, which are allindependently attached to the optic transition area. Therefore, if onehaptic is positioned against tissue that is smaller in diameter than thetissue where another haptic is resting, the movement of one haptic doesnot cause the second haptic to have substantially less or more force tohold the lens haptic in position. This fact gives the lens extremelygood centration. In this embodiment Of the present invention, thehaptics may be optionally crossed.

[0135] The success of the crossed haptic design is due to the length ofthe haptics and its small cross sectional area. The flexibility of thehaptic is proportional to the third power of the length of the haptic.Therefore, this embodiment lengthens the haptic without moving thehaptics more than the width of the incision away from the centerline ofthe haptic transition area. At the radial distal end of the haptictransition area where the haptics are split into two members, 6, theoutside width of the two combined haptics cannot be wider than thedesired incision size to implant the lens.

[0136] The haptic arms, 6, 60, extend radially outward to a positionwhere the change in direction, 7, occurs before contacting tissue whenthe lens is placed in the eye. In addition to increasing the haptic armdistance, the haptic arm width and thickness are controlled. Thethickness of the haptic arm controls the amount of movement of the lensin the axial direction (i.e., it controls axial anterior displacement).The thicker the haptic arm, the less anterior displacement will occur.Due to the fact that thickness is inversely proportional to the thirdpower of the thickness, when forces acting to bend the haptic along theaxial plan is applied, there is much less anterior displacement of theoptic.

[0137] When considering force applied to bend the haptics in a radialplane the deflection of the lens haptic is inversely proportional to thethird power of the width of the haptic. Therefore to obtain the desireddimensions the haptics approach the thickness of the current state ofthe art lens, but are significantly thinner in width. This allows thelens haptic to have good strength, while being very rigid in the axialdirection, yet being extremely flexible in the radial direction. Sincethe lens design reduces the amount of force required to flex the lensthe haptic footplates, 11, can be significantly thinner. For a standardstate of the art lens, the footplates are between 200 and 250 microns.

[0138] The large footplates block the trabecular meshwork and addsignificant force to Schlemm's Canal at the contact points of thefootplates. This embodiment of the present lo invention allows the useof a footplate that is about 50 or less microns thick.

[0139] The haptic arms, 60, are bent to where the haptic arms and thehaptic footplates, 70, are inside the optic area, 20. The optic area isthen rolled with the haptics remaining inside. The rolled optic thenacts as a guide or conduit to carry the haptics through the wound. Asthe optic is inserted through the wound the wound holds the optic rolleduntil the optic starts opening inside the eye. As the optic opens thehaptics are freed to move into position within the eye. The opticconfiguration is covered under patent application Ser. No. 08/914,767,incorporated herein by reference.

[0140] Preferred embodiments of the present invention are thin lensoptics where the optic when made of PMMA, are approximately 15-35microns thick, preferably about 22-28, and more preferably about 25microns thick at the thinnest point and about 75-95 microns thick,preferably about 82-87 microns thick, most preferably about 85 micronsthick at the thickest point. The optic diameter is approximately 40-60microns thick, preferably about 45-55, and most preferably about 50microns thick. The haptic transition area starts at about the thicknessof the optic diameter (most preferably about 50 microns) and increasesin thickness about three times (preferably to about 150 microns thick).At the point where the haptic transition thickness reaches the desiredthickness, the haptic transition area has reached a width ofapproximately 400-700 microns, preferably about 450-550, most preferablyabout 500 microns. After flexing the haptics, the radially distal mostpart of the curve should be less than the width of the desired incision.For the preferred embodiment the desired incision is about 3millimeters. To obtain the desired flexibility the width of the hapticis preferably about 100 microns wide. The length of the haptic radiallyfrom the center of the optic to where the haptic changes direction ispreferably about 5.5 millimeters. The curve at the end of the radial armof the haptic is about 375 microns in radius and traverses about 52degrees of arc. The desired width in conjunction with the desired hapticlengths and shapes allows the lens to have approximately 900 milligramsapplied force to flex the lens three millimeters (the preferred incisionsize). After twenty-four hours of flexure, the lens has less than 200milligrams of force. The footplates are one millimeter in diameter,which is the same as the current state of the art; however, thethickness of the footplate is 50 microns.

[0141] As discussed above, the lens material may also be constructed outof PMMA, but all the lens of the present invention may also beoptionally constructed from any other biologically compatible material.Additionally, the lens optics of the present invention may have varyingdegrees of convexity or concavity to help obtain particular focusingpowers.

[0142] All patents, copending applications, articles and publicationsreferred to above are herein expressly incorporated by reference.

[0143] The invention thus being described, it would be obvious that thesame may be modified in ways that would be understood by one of ordinaryskill in the art, It is to be understood that the present invention isnot limited to the embodiments described above, and includes suchvariations. As such, all such variations are intended to be within thescope of the following claims.

We claim:
 1. An intraocular lens, comprising: a lens optic; a first pairof haptic arms attached to said optic; a second pair of haptic armsattached to said optic at a diametrically opposite point to the firstpair of haptic arms; wherein the haptic arms in each respective pairextend radially from the optic and parallel one arm to the other to theradial distal end before each haptic sweeps around the periphery of theoptic; and each haptic arm crosses the haptic arm attached to thediametrically opposite stem on the same side of an axis running throughthe center of said diametrically opposite point.
 2. The intraocular lensof claim 1, wherein each of said pairs of haptic arms are connected tothe lens optic via a stem.
 3. The intraocular lens of claim 1, whereineach said haptic is connected independently to the lens optic.
 4. Theintraocular lens of claim 1, wherein said intraocular lens is made froma resilient, deformable material, whereby said lens regains its shapeafter being compressed, bent, folded, rolled or stretched.
 5. Theintraocular lens of claim 1, wherein said haptics further comprisefootplates which slightly protrude lateral to the outside edges of saidhaptic arms, whereby the surface area of said haptic arms in contactwith and the pressure applied to the tissue of the eye is minimized. 6.The intraocular lens of claim 1, wherein said lens optic is vaultedanteriorly and adapted for implantation in the anterior chamber of anaphakic eye.
 7. The intraocular lens of claim 1, wherein said lens opticis vaulted posteriorly and adapted for implantation in the posteriorchamber of an aphakic eye.
 8. The intraocular lens of claim 1, whereinsaid lens optic is vaulted anteriorly and adapted for implantation inthe anterior chamber of an phakic eye.
 9. The intraocular lens of claim1, wherein said lens optic is vaulted posteriorly and adapted forimplantation in the posterior chamber of an phakic eye.
 10. A method ofimplanting an intraocular lens in a human eye, comprising: attaching asuture material to an intraocular lens in a human eye; inserting saidlens into the eye through an incision in the eye; and irrigating saidsuture material, whereby the suture material releases the lens.
 11. Themethod of claim 10, wherein said intraocular lens, comprises: a lensoptic; a first pair of haptic arms attached to said optic; a second pairof haptic arms attached to said optic at a diametrically opposite pointto the first pair of haptic arms; wherein the haptic arms in eachrespective pair extend radially from the optic and parallel one arm tothe other to the radial distal end before each haptic sweeps around theperiphery of the optic; and each haptic arm crosses the haptic armattached to the diametrically opposite stem on the same side of an axisrunning through the center of said diametrically opposite point.
 12. Themethod of claim 11, wherein said incision is about 3 mm or less inlength.
 13. The method of claim 11, wherein said insertion step includesinserting the intraocular lens optic in the posterior chamber of an eye.14. The method of claim 11, wherein said insertion step includesinserting the intraocular lens in the anterior chamber of an eye.
 15. Anintraocular lens, comprising: a lens optic; four haptics independentlyattached to the lens optic, wherein the movement of or pressure appliedby eye tissue to a first haptic does not substantially influence asecond haptic's contact with eye tissue.
 16. The intraocular lens ofclaim 15, further comprising a footplate at the end of each optic, saidfootplate having a thickness of about 50 microns or less and having adiameter of about 1 millimeter.
 17. The intraocular lens of claim 15,wherein the thickness of the lens optic around its edges is about 50millimeters.
 18. The intraocular lens of claim 15, wherein the fourhaptics are attached to the lens optic through a transitional area, saidtransitional area having a first thickness of about that of the edge ofthe lens optic and expanding to a thickness of about three times thefirst thickness at a distance from the edge of the lens optic.
 19. Theintraocular lens of claim 15, wherein the haptic width is smaller thanthe haptic height.
 20. An intraocular lens, comprising: a lens optichaving a thickness of about 15 microns to about 95 microns, and havingan optic diameter of about 60 microns or less; four hapticsindependently attached to the lens optic, said haptics comprising afootplate distally located from the point of attachment to the lensoptic; and wherein the four haptics are attached to the lens optic inpairs of two, each pair having a line of symmetry separated from theother by approximately 180 degrees.
 21. The intraocular lens of claim20, wherein said four haptics are attached to the lens optic through atransitional area, wherein the transitional area has substantially thesame thickness of the optic edge, and decreases in width and increasesin thickness at a distance from the optic edge.
 22. The intraocular lensof claim 21, wherein the transitional area, at a point distal to theoptic edge, increases in thickness to three times the thickness of theoptic edge.
 23. The intraocular lens of claim 20, wherein the length ofthe haptic arm is proportional to the flexibility of the haptic arm. 24.The intraocular lens of claim 20, wherein each pair of haptics extendfrom the optic parallel one haptic to the other for a distance beforeextending symmetrically around the circumference of the optic inopposite directions to a point about 15-30 degrees from a center line inthe optic that is perpendicular to the point where the haptics areattached to the optic.
 25. The intraocular lens of claim 20, wherein thehaptic vault is less than about 25 microns when flexed three metersradially.
 26. The intraocular lens of claim 20, wherein the footplatesdo not block trabecular meshwork or Schlemm's Canal when inserted intothe eye and resting upon eye tissue.
 27. The intraocular lens of claim20, wherein, after insertion into an eye, the amount of stress or forcerequired to hold the lens optic in position decreases with time to lessthan about 25 percent of the initial force.
 28. The intraocular lens ofclaim 27, wherein the force applied to hold the optic in position withinthe eye after 24 hours from insertion is less than about 200 milligrams.29. The intraocular lens of claim 21, wherein the transitional area hasa thickness of about 50 microns at the edge of the lens optic, and has athickness of about 150 microns at its thickest point at a distance fromthe lens optic.
 30. The intraocular lens of claim 21, wherein thetransitional area has a width of about 500 microns or less at the pointdistal to the lens optic where the transitional area has reached itsthickest point.
 31. The intraocular lens of claim 20, wherein, afterflexing the haptics, the width of the intraocular lens is about 3millimeters or less.
 32. The intraocular lens of claim 24, wherein thelength of the first and second haptic in a pair radially from the centerof the optic to the point where the first haptic turns opposite thesecond haptic is about 5.5 millimeters;
 33. The intraocular lens ofclaim 32, wherein the curve at the end of the radial arm of the hapticis about 375 microns in radius and traverses about 52 degrees of arc.34. An intraocular lens, comprising: a lens optic; two pairs of hapticsattached to the lens optic, each pair being located at a diametricallypoint about 180 degrees from the other; a footplate at a point on eachhaptic distally located from the optic; wherein said lens optic is from15-95 microns thick, with a diameter of about 50 microns thick; whereineach pair of haptics is attached to the lens optic through atransitional area that starts at a thickness of that of the lens opticdiameter, and expands to three times the thickness of the lens opticdiameter at a distance from the lens optic diameter; and wherein thehaptics in the pair extend from the lens optic in a parallel manner onehaptic to the other for a distance of about 5.5 millimeters beforeturning opposite directions around the edge of the lens.
 35. Theintraocular lens of claim 34, wherein the diameter of the lens optic isabout 50 microns.
 36. The intraocular lens of claim 34, wherein thehaptic width is about 100 microns.
 37. The intraocular lens of claim 34,wherein said lens has less than 300 milligrams of force after 24 hoursof flexure.
 38. The intraocular lens of claim 34, wherein said footplateis 1 millimeter in diameter and 50 microns thick.
 39. The intraocularlens of claim 34, wherein said haptics, after turning an oppositedirection from the corresponding haptic in its pair, moves to a pointapproximately 15-30 degrees from a center line in the lens optic. 40.The intraocular lens of claim 34, wherein said haptics, after turning anopposite direction from the corresponding haptic in its pair, moves to apoint approximately 25 degrees from a center line in the lens optic.